Move BTN and 2 Listboxes, move data on click of moveBtn code

Need help with code in the following project using Visual Basics 2013 in WPF.

Create 2 list boxes and a button labeled MOVE.
Put the following data into list box 1 using the String Editor - MD VA NC SC WV PA NJ DE and set the list box to sort the data.
The second list box will be empty to start.  The first list box will not have any item selected at the start.
When the user clicks MOVE, check to see if an item is selected. If not dispaly a message box with the message "You must select an item."
If an item is selected check to see if the item already exists in list box 2. If not add the item to list box 2. If the item already exists in list box 2 then display a message box with the message "The item you selected XX already exists in the second list box." where XX is replaced with the item selected